Electrical connectors are well known in the art for interconnecting a primary printed circuit board (often called a "mother" board) and a secondary printed circuit board (often called a "daughter" board). The connections between the two circuit boards typically are made along an edge of the secondary circuit board which, therefore, commonly is referred to as an edge card.
Such edge card connectors typically include an insulating or dielectric housing mountable on the primary or mother board. The housing has a card-receiving slot for receiving the edge of the secondary or daughter board. A plurality of terminals are mounted on the housing along one or both sides of the slot, and the terminals have flexible contact portions projecting into the slot for engaging appropriate circuit traces on one or both sides of the secondary circuit board.
One of the problems with edge card connectors as described above is that the sharp edge of the inserted edge card engages and wipes the flexible contact portions of the terminals during insertion of the edge card into the card-receiving slot in the housing. At least the contact portions of the terminals typically are plated with a highly conductive precious metal. The substrate of the edge card typically is fabricated of abrasive material, such as glass fibers. If the lead-in edge of the card engages and wipes over the plated contact portions, degradation of the contact plating occurs.
In order to solve the above-identified problem, zero insertion force (ZIF) connectors have been designed such the edge card is inserted into the card-receiving slot of the connector with zero or minimum wiping action on the plated contact portions of the terminals. In some connectors, minimum wiping action still is afforded to remove oxidation at the contact surfaces, but the forces are not sufficient for the edge card to significantly damage the plating of the contact surfaces. Heretofore, such ZIF connectors have been fairly complicated because actuators, springs, cams and other devices are mounted on the connector housing to effect terminal or contact engagement after the edge card is fully inserted into the card-receiving slot of the housing. The present invention is directed to solving these problems by a very simple, efficient, cost-effective and unique system which employs a simple actuator mounted on and carried by the edge card, itself and allows at the same time to use a wide variety of daughter board thicknesses without degradation of the spring performance of the connector.